The synthesis and reactions of dihydropyridines, which can be regarded as model compounds for the coenzyme NADH, will be studied in order to gain a better understanding of the mode of action of the coenzyme. The new dihydropyridines would be useful for the preparation of NADH analogs. Since a number of dihydropyridines have shown promising biological activity the compounds will be subjected to pharmacological testing. Synthetic methods will include ring formation via acetylenes, reduction and addition of nucleophiles to pyridines and pyridinium salts, and attachment of substituents to the nitrogen via dihydropyridine anions. The catalytic and photochemical isomerisation of 1,2- and 1,4-dihydropyridines will be attempted, and, if successful, used to establish relative stabilities of pairs of isomers. The properties of dihydropyridines will be examined, with particular emphasis on hydrogen transfer (including some quantitative aspects), addition reactions and protonation.